1. Field of the Invention
The present invention relates generally to a mounting arrangement of an engine and an associated power train for an automotive vehicle. More specifically, the present invention relates to a mounting arrangement of a vehicular engine and an associated power train including a transmission and a differential gear unit, wherein the engine, the transmission and the differential gear unit are transversely disposed relative to a longitudinal axis of the vehicle and in parallel with one another.
2. Description of the Background Art
A mounting arrangement for an automotive vehicle with transversly disposed engine, transmission and differential gear unit is known in the art as disclosed, for example, in U.S. Pat. No. 4,223,569.
In the above-noted patent, an engine is disposed at the front of a front wheel drive vehicle with an axis of an engine crankshaft extending transversely to a longitudinal axis of the vehicle. A torque converter is arranged adjacent to the engine with its axis being aligned with the axis of the engine crankshaft for a power transmission therefrom. At the rear of the engine and the torque converter, a gear train of a transmission is disposed with its axis parallel to the axis of the engine crankshaft or the torque converter. An output power of the torque converter is transmitted to an input shaft of the transmission gear train by means of a sprocket-chain connection therebetween. Further, a differential gear unit is disposed adjacent to the transmission gear train with its axis being aligned with the axis of the transmission gear train for a power transmission therefrom.
In the above-noted mounting arrangement, however, since the transmission gear train and the differential gear unit are transversely arranged with their axes being aligned with each other, a degree of freedom for mounting other vehicular components, such as, various components of a suspension system, is so limited in a transverse or width direction of the vehicle.
Further, assuming that the above-noted mounting arrangement is applied to a four wheel drive vehicle, a transfer unit is further disposed adjacent to the differential gear unit with its axis being aligned with the axis of the differential gear unit for a power transmission therefrom. Accordingly, a location of the transfer unit is caused to be offset or deviated laterally from the lateral center of the vehicle. The transfer unit controls a power distribution to be transmitted to rear wheels through a propeller shaft and a rear wheel differential gear unit. The propeller shaft extends axially between the transfer unit and the rear wheel differential gear unit. As a result, the propeller shaft is inevitably offset or deviated laterally from the lateral center of the vehicle, so that no space for a brake pedal is provided at one lateral side of the vehicle due to existence of a floor projection or tunnel for accommodating the offset propeller shaft underneath a vehicle floor. Accordingly, a problem has been raised that the same layout of the foregoing vehicular components can not satisfy both right and left steering wheel vehicles due to no space for the brake pedal at the one lateral side of the vehicle.
On the other hand, if the differential gear unit is disposed at the rear of the transmission gear train so as to arrange the propeller shaft to extend axially at the lateral center of the vehicle, a problem is raised in that a weight distribution to front wheels increases deteriorating controllability of the steering as well as durability of front tires due to an inevitable forward location change of the engine, which is far forward of axes of the front wheels, and due to a corresponding increased front overhang.
Another mounting arrangement has been proposed, wherein the axis of the engine crankshaft is arranged above and forward of the axis of the transmission gear train, and the axis of the differential gear unit is arranged rearward of and level with the axis of the transmission gear train. In this arrangement, however, since the engine is still inevitably located considerably forward of the axes of the front wheels, a corresponding large weight distribution to the front wheels as well as the corresponding increased overhang are resulted. In addition, since the engine is located substantially over the transmission gear train, a higher engine hood line results, narrowing front visibility, and further results in insufficient space for an engine oil pan.